<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        arr = [
            { id: "29", pid: '', name: '总裁办' },
            { id: "2c", pid: '', name: '财务部' },
            { id: "2d", pid: '2c', name: '财务核算部' },
            { id: "2f", pid: '2c', name: '薪资管理部' },
            { id: "d2", pid: '', name: '技术部' },
            { id: "d3", pid: 'd2', name: 'java研发部' }
        ]
     
        function change(arr,pid){

            const list = arr.filter( item => {
                if (item.pid === pid ) {
                    return true
                }else{
                    return false
                }
            })
            // console.log(list);

            list.forEach(item => {
                item.children = change(arr, item.id)
            });
            return list
        }

          const newArr = change(arr,'')
          console.log(newArr);
    </script>
</body>

</html>